EP0566768A1 - Control circuit for a gas burner with a flow switch for monitoring the air supply - Google Patents
Control circuit for a gas burner with a flow switch for monitoring the air supply Download PDFInfo
- Publication number
- EP0566768A1 EP0566768A1 EP92107000A EP92107000A EP0566768A1 EP 0566768 A1 EP0566768 A1 EP 0566768A1 EP 92107000 A EP92107000 A EP 92107000A EP 92107000 A EP92107000 A EP 92107000A EP 0566768 A1 EP0566768 A1 EP 0566768A1
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- European Patent Office
- Prior art keywords
- relay
- control circuit
- series
- diode
- circuit according
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/24—Preventing development of abnormal or undesired conditions, i.e. safety arrangements
- F23N5/242—Preventing development of abnormal or undesired conditions, i.e. safety arrangements using electronic means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
- F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
- F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
- F23N2005/182—Air flow switch
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/22—Timing network
- F23N2223/26—Timing network with capacitors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/22—Timing network
- F23N2223/28—Timing network with more than one timing element
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/04—Prepurge
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/22—Pilot burners
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/36—Spark ignition, e.g. by means of a high voltage
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2229/00—Flame sensors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2233/00—Ventilators
- F23N2233/06—Ventilators at the air intake
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
Definitions
- the invention relates to a control circuit for gas burners according to the preamble of claim 1.
- Conventional control circuits of this type switch the blower on via the normally closed contact of the flow switch as soon as the correct operation of the flame sensor has been checked.
- the flow switch is checked with the least possible amount of circuitry before the blower is put into operation, so that a proper combustion air supply is not simulated despite the flow switch or blower being inoperative.
- the invention characterized in claim 1 does not require relays equipped with several contact sets, but is content with relays with a single-pole changeover contact. Nevertheless, the circuit arrangement is intrinsically safe and is characterized by particularly low circuit complexity. Advantageous embodiments of the invention result from the subclaims.
- the control circuit comprises a flame sensor circuit FS, a fan FA, a flow switch PS, an ignition gas valve PV, a main gas valve MV, an ignition circuit Z, a first relay RY02 and a second relay RY01.
- the make contact PNO of the flow switch PS is connected to the live via the make contact NO2 of the first relay RY02 Terminal L of an AC voltage source is connected, the return line N of which is connected to ground.
- the fan FA is also switched between the aforementioned NO2 contact of the first relay RY02 and ground.
- the normally closed contact NC2 of the first relay RY02 is connected via a resistor R01, for example 68kOhm, on the one hand to a diode D04 and on the other hand via a resistor R05, for example 68kOhm, to a charging capacitor C05, for example 22uF.
- the diode D04 is on the other hand at the normally closed contact PNC of the flow switch PS.
- the excitation winding of the pilot burner valve PV is connected between the changeover contact PC of the flow switch PS and ground N.
- the series connection of the field winding RY02 of the first relay with an electronic switch in the form of a transistor Q02 is connected in parallel with the charging capacitor C05. Furthermore, a further electronic switch Q03 in the form of a further transistor is connected in parallel to the charging capacitor C05, the base electrode of which is supplied with a switch-on signal for the control circuit via the input IN.
- the flame monitoring circuit FS is connected in series with the high-voltage winding of the ignition transformer T1 with its input E to the ignition electrode HT.
- the HT electrode serves both as an ignition electrode and as a flame rod for flame monitoring.
- the voltage-dependent resistor RV01 represents a short circuit for the low-frequency high-voltage pulses and acts as an insulator for the low-voltage ionization direct current of the flame rod.
- the output A of the flame monitoring circuit FS is connected to ground N with a low resistance in the absence of a flame. As soon as a signal indicating the presence of a flame at input E stands, this low-resistance connection of output A to ground is interrupted or at least high-resistance.
- the tap between the two resistors R13 and R15 mentioned is at the non-inverting input (+) of the comparator IC1.
- the inverting input (-) of this comparator is connected on the one hand to the tap of a voltage divider consisting of the resistors R08, for example 1MOhm and R07, for example 680kOhm, which is connected between the supply voltage (+ Vc) and ground N.
- this input (-) is connected via a resistor R11, e.g. 68kOhm, and a diode D08 connected to the connection point between relay RY02 and transistor Q02.
- the output of the comparator is also connected to the DC supply voltage (+ Vc) via a resistor R10, for example 100 kOhm, and is also connected to the control electrode, i.e. led to the base of transistor Q02.
- a second relay RY01 is connected in series with an electronic switch in the form of a further transistor Q01 and a second charging capacitor C01, for example 100uF.
- This parallel connection is connected via an overtemperature limiter HL and a resistor R02 of, for example, 18 kOhm and a diode D01 to the normally open contact N02 of the first relay RY02.
- a Zener diode Z01 is connected in parallel with the charging capacitor C01 via the overtemperature limiter HL.
- a Resistor R06 for example of 220 kOhm, connects the output of the flame monitoring circuit FS to the temperature limiter HL and thus also to the relay RY01 and the charging capacitor C01.
- the normally closed contact NC1 of the relay RY01 connects the ignition circuit Z to the changeover contact PC of the flow switch PS.
- the normally open contact NO1 connects the field winding of the main burner valve MV to the changeover contact PC.
- the circuit arrangement works as follows: The circuit shows that switching on the contact ry02 of the relay RY02 is necessary to switch on the fan FA. This relay can only respond when transistor QO2 is on and transistor QO3 is off. For this purpose, the base of the transistor QO3 must be supplied with a switch-on signal which is negative with respect to ground N at the input IN. In this case, the capacitor C05 is charged by the positive half-wave of the AC voltage at the supply voltage terminal L via the resistors R01 and R05, while the negative half-wave by ground N via the field winding PV of the pilot burner valve, the normally closed contact PNC of the flow switch PS and the diode D04 and resistor R01 flows to terminal L. The pilot burner valve PV is not activated by this current.
- capacitor C05 could not be charged. It is charged until the voltage at the non-inverting input (+) of the comparator IC1 exceeds that at the inverting input (-). In this case, the output of the comparator IC01 assumes a high impedance, so that a current flows from the voltage source (+ Vc) via the resistor R10 into the base of the transistor QO2 and turns it on. The charge on capacitor C05 is sufficient to trigger relay RY02 when transistor Q02 is turned on. Its changeover contact ry02 switches from normally closed contact NC2 to normally open contact NO2. The fan FA is now connected to the AC supply voltage L via the latter contact and starts up.
- a positive current i1 flows from line L via contact NO2, diode DO2, resistor RO2 and from there into capacitor CO1, as long as the voltage across this capacitor is less than the breakdown voltage of zener diode Z01. If the voltage across capacitor CO1 exceeds the voltage across Zener diode Z01, current i1 flows through Zener diode Z01, relay RY02 and transistor Q02 to ground. This current i1 serves as a holding current for the relay RY02.
- the flow switch PS switches from the normally closed contact PNC to the normally open contact PNO, so that the excitation winding PV of the pilot burner valve is now supplied with current, the valve opens and gas flows to the pilot burner.
- the ignition circuit Z receives voltage via the normally closed contact NC1 of the relay RY01 and generates high-voltage ignition sparks to earth GND via the ignition transformer T1 in series with a voltage-dependent resistor RV01 at the ignition electrode HT.
- an ionization current flows to the input E of the flame sensor circuit FS from the flame rod electrode HT via the secondary winding of the transformer T1, so that the output A of the flame sensor circuit FS switches to a high impedance.
- the current through resistor R06 now flows no longer via the output A and the flame sensor circuit to ground N, but via the diode D06 into the base of the transistor Q01, so that it switches through.
- the charge stored on capacitor C01 can thus trigger relay RY01. Since the voltage drop generated by the current i1 at the relay RY01 is less than the voltage at the zener diode Z01, the current i1 flows fully through the relay RY01 and is sufficient to keep the relay activated. If transistor Q01 is short-circuited due to an error, relay RY01 cannot respond.
- the relay RY01 drops out, as a result of which the main gas valve MV is de-energized and closes.
- the pilot burner continues to be supplied with gas. Since the pilot flame continues to burn, the transistor Q01 remains on.
- the relay RY01 cannot respond again because the capacitor C01 could not be charged to a sufficiently high voltage during the switch-off period. It was in fact short-circuited and discharged via the relay winding RY01 and the transistor Q01 during the cooling down period. To switch the system on again, the AC mains voltage must therefore either be interrupted or the input signal IN temporarily switched off. so that the relay RY02 drops out and the pilot light goes out.
- the burner can only be started when the flow switch PS is initially in the rest position in which its normally closed contact PNC is closed. Furthermore, a negative input signal IN must be present and the transistor Q03 must therefore be blocked. Finally, a third condition is that the flame sensor circuit FS does not detect a flame. If one of these conditions is not met, the control circuit cannot start. If, for example, the flow switch with its changeover contact is connected to the make contact PNO, the capacitor C05 is not charged because the diode D04 has no effect. If the transistor Q03 were turned on due to a positive input signal, it would short-circuit the capacitor C05, so that it could not be charged either.
- the flow switch PS forms with its normally closed contact PNC together with the resistors R01 and R04 as well as the diode D04 and the pilot burner valve PV a charging circuit for the capacitor C05, which provides the energy required to switch on the relay RY02.
- the make contact PNO of the flow switch serves to switch on the pilot burner valve PV after the relay RY02 has responded.
- the circuit arrangement is largely intrinsically safe. It can be switched on by a low-voltage control signal at the IN input without an additional relay and can therefore be controlled directly from an electronic temperature controller.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Combustion (AREA)
- Regulation And Control Of Combustion (AREA)
Abstract
Description
Die Erfindung betrifft eine Steuerschaltung für Gasbrenner gemäß Gattungsbegriff des Anspruchs 1. Herkömmliche Steuerschaltungen dieser Art schalten das Gebläse über den Ruhekontakt des Strömungsschalters ein, sobald der ordnungsgemäße Betrieb des Flammenfühlers geprüft ist. Mit der Erfindung wird bei geringstmöglichem Schaltungsaufwand vor der Inbetriebsetzung des Gebläses der Strömungsschalter überprüft, damit nicht etwa trotz funktionsunfähigem Strömungsschalter oder Gebläse eine vorschriftsmäßige Verbrennungsluftzufuhr vorgetäuscht wird. Die im Anspruch 1 gekennzeichnete Erfindung benötigt keine mit mehreren Kontaktsätzen ausgerüstete Relais, sondern begnügt sich mit Relais mit einem einpoligen Umschaltkontakt. Gleichwohl ist die Schaltungsanordnung eigensicher und zeichnet sich durch besonders geringen Schaltungsaufwand aus. Vorteilhafte Ausgestaltungen der Erfindung ergeben sich aus den Unteransprüchen.The invention relates to a control circuit for gas burners according to the preamble of claim 1. Conventional control circuits of this type switch the blower on via the normally closed contact of the flow switch as soon as the correct operation of the flame sensor has been checked. With the invention, the flow switch is checked with the least possible amount of circuitry before the blower is put into operation, so that a proper combustion air supply is not simulated despite the flow switch or blower being inoperative. The invention characterized in claim 1 does not require relays equipped with several contact sets, but is content with relays with a single-pole changeover contact. Nevertheless, the circuit arrangement is intrinsically safe and is characterized by particularly low circuit complexity. Advantageous embodiments of the invention result from the subclaims.
Die Erfindung wird nachfolgend anhand eines in der Zeichnung wiedergegebenen Ausführungsbeispiels erläutert. Die Steuerschaltung umfaßt einen Flammenfühlerschaltkreis FS, ein Gebläse FA, einen Strömungsschalter PS, ein Zündgasventil PV, ein Hauptgasventil MV, einen Zündstromkreis Z, ein erstes Relais RY02, sowie ein zweites Relais RY01. Der Arbeitskontakt PNO des Strömungsschalters PS ist über den Arbeitskontakt NO2 des ersten Relais RY02 an die spannungsführende Klemme L einer Wechselspannungsquelle angeschlossen, deren Rückleitung N an Masse liegt. Das Gebläse FA ist ebenfalls zwischen den genannten Arbeitskontakt NO2 des ersten Relais RY02 und Masse eingeschaltet. Der Ruhekontakt NC2 des ersten Relais RY02 steht über einen Widerstand R01, von beispielsweise 68kOhm, einerseits mit einer Diode D04 und andererseits über einen Widerstand R05, von z.B. 68kOhm, mit einem Ladekondensator C05, von beispielsweise 22uF, in Verbindung. Die Diode D04 liegt andererseits am Ruhekontakt PNC des Strömungsschalters PS. Die Erregerwicklung des Zündbrennerventils PV ist zwischen den Umschaltkontakt PC des Strömungsschalters PS und Masse N eingeschaltet.The invention is explained below with reference to an embodiment shown in the drawing. The control circuit comprises a flame sensor circuit FS, a fan FA, a flow switch PS, an ignition gas valve PV, a main gas valve MV, an ignition circuit Z, a first relay RY02 and a second relay RY01. The make contact PNO of the flow switch PS is connected to the live via the make contact NO2 of the first relay RY02 Terminal L of an AC voltage source is connected, the return line N of which is connected to ground. The fan FA is also switched between the aforementioned NO2 contact of the first relay RY02 and ground. The normally closed contact NC2 of the first relay RY02 is connected via a resistor R01, for example 68kOhm, on the one hand to a diode D04 and on the other hand via a resistor R05, for example 68kOhm, to a charging capacitor C05, for example 22uF. The diode D04 is on the other hand at the normally closed contact PNC of the flow switch PS. The excitation winding of the pilot burner valve PV is connected between the changeover contact PC of the flow switch PS and ground N.
Dem Ladekondensator C05 ist die Reihenschaltung der Erregerwicklung RY02 des ersten Relais mit einem elektronischen Schalter in Form eines Transistors Q02 parallelgeschaltet. Weiterhin ist dem Ladekondensator C05 ein weiterer elektronischer Schalter Q03 in Form eines weiteren Transistors parallelgeschaltet, dessen Basiselektrode über den Eingang IN ein Einschaltsignal für die Steuerschaltung zugeleitet wird.The series connection of the field winding RY02 of the first relay with an electronic switch in the form of a transistor Q02 is connected in parallel with the charging capacitor C05. Furthermore, a further electronic switch Q03 in the form of a further transistor is connected in parallel to the charging capacitor C05, the base electrode of which is supplied with a switch-on signal for the control circuit via the input IN.
Die Flammenüberwachungsschaltung FS ist in Reihe mit der Hochspannungswicklung des Zündtransformators T1 mit ihrem Eingang E an die Zündelektrode HT angeschlossen. Die Elektrode HT dient sowohl als Zündelektrode als auch als Flammenstab zur Flammenüberwachung. Der spannungsabhängigen Widerstand RV01 stellt für die niederfrequenten Hochspannungsimpulse einen Kurzschluß dar und wirkt für den Niedervolt-Ionisations-Gleichstrom des Flammenstabs wie ein Isolator. Der Ausgang A der Flammenüberwachungsschaltung FS ist bei fehlender Flamme niederohmig mit Masse N verbunden. Sobald ein das Vorhandensein einer Flamme anzeigendes Signal am Eingang E steht, wird diese niederohmige Verbindung des Ausgangs A nach Masse unterbrochen oder zumindest hochohmig.The flame monitoring circuit FS is connected in series with the high-voltage winding of the ignition transformer T1 with its input E to the ignition electrode HT. The HT electrode serves both as an ignition electrode and as a flame rod for flame monitoring. The voltage-dependent resistor RV01 represents a short circuit for the low-frequency high-voltage pulses and acts as an insulator for the low-voltage ionization direct current of the flame rod. The output A of the flame monitoring circuit FS is connected to ground N with a low resistance in the absence of a flame. As soon as a signal indicating the presence of a flame at input E stands, this low-resistance connection of output A to ground is interrupted or at least high-resistance.
Ein Spannungsteiler bestehend aus den Widerständen R13, von beispielsweise 6,8MOhm, und R15, von beispielsweise 2,2MOhm, liegt zwischen dem Verbindungspunkt von Ladekondensator C05 und erstem Relais RY02 einerseits und dem Ausgang A des Flammenüberwachungsschaltkreises FS andererseits. Der Abgriff zwischen den beiden genannten Widerständen R13 und R15 liegt am nicht invertierenden Eingang (+) des Vergleichers IC1. Der invertierende Eingang (-) dieses Vergleichers steht einerseits mit dem Abgriff eines aus den Widerständen R08, von beispielsweise 1MOhm und R07, von beispielsweise 680kOhm, bestehenden Spannungsteilers in Verbindung, der zwischen die Versorgungsspannung (+Vc) und Masse N eingeschaltet ist. Andererseits ist über dieser Eingang (-) über einen Widerstand R11, von z.B. 68kOhm, und eine Diode D08 an den Verbindungspunkt zwischen Relais RY02 und Transistor Q02 angeschlossen. Der Ausgang des Vergleichers liegt über einen Widerstand R10, von beispielsweise 100kOhm, ebenfalls an der Versorgungsgleichspannung (+Vc) und ist außerdem an die Steuerelektrode, d.h. an die Basis des Transistors Q02 geführt.A voltage divider consisting of the resistors R13, for example 6.8MOhm, and R15, for example 2.2MOhm, lies between the connection point of the charging capacitor C05 and the first relay RY02 on the one hand and the output A of the flame monitoring circuit FS on the other. The tap between the two resistors R13 and R15 mentioned is at the non-inverting input (+) of the comparator IC1. The inverting input (-) of this comparator is connected on the one hand to the tap of a voltage divider consisting of the resistors R08, for example 1MOhm and R07, for example 680kOhm, which is connected between the supply voltage (+ Vc) and ground N. On the other hand, this input (-) is connected via a resistor R11, e.g. 68kOhm, and a diode D08 connected to the connection point between relay RY02 and transistor Q02. The output of the comparator is also connected to the DC supply voltage (+ Vc) via a resistor R10, for example 100 kOhm, and is also connected to the control electrode, i.e. led to the base of transistor Q02.
Ein zweites Relais RY01 ist in Reihe mit einem elektronischen Schalter in Form eines weiteren Transistors Q01 einem zweiten Ladekondensator C01, von beispielsweise 100uF parallelgeschaltet. Diese Parallelschaltung steht über einen Übertemperaturbegrenzer HL sowie einen Widerstand R02 von beispielsweise 18kOhm und eine Diode D01 mit dem Arbeitskontakt N02 des ersten Relais RY02 in Verbindung. Außerdem ist über den genannten Übertemperaturbegrenzer HL eine Zenerdiode Z01 dem Ladekondensator C01 parallelgeschaltet. Ein Widerstand R06, von beispielsweise 220kOhm, verbindet den Ausgang des Flammenüberwachungsschaltkreises FS mit dem Temperaturbegrenzer HL und damit auch mit dem Relais RY01 und dem Ladekondensator C01.A second relay RY01 is connected in series with an electronic switch in the form of a further transistor Q01 and a second charging capacitor C01, for example 100uF. This parallel connection is connected via an overtemperature limiter HL and a resistor R02 of, for example, 18 kOhm and a diode D01 to the normally open contact N02 of the first relay RY02. In addition, a Zener diode Z01 is connected in parallel with the charging capacitor C01 via the overtemperature limiter HL. A Resistor R06, for example of 220 kOhm, connects the output of the flame monitoring circuit FS to the temperature limiter HL and thus also to the relay RY01 and the charging capacitor C01.
Der Ruhekontakt NC1 des Relais RY01 schließt den Zündstromkreis Z an den Umschaltkontakt PC des Strömungsschalters PS an. Der Arbeitskontakt NO1 hingegen verbindet die Erregerwicklung des Hauptbrennerventils MV mit dem genannten Umschaltkontakt PC.The normally closed contact NC1 of the relay RY01 connects the ignition circuit Z to the changeover contact PC of the flow switch PS. The normally open contact NO1, on the other hand, connects the field winding of the main burner valve MV to the changeover contact PC.
Die Schaltungsanordnung arbeitet folgendermaßen:
Die Schaltung läßt erkennen, daß für das Einschalten des Gebläses FA ein Umschalten des Kontakts ry02 des Relais RY02 erforderlich ist. Dieses Relais kann nur ansprechen, wenn der Transistor QO2 durchgeschaltet und der Transistor QO3 gesperrt ist. Der Basis des Transistors QO3 muß hierzu ein gegenüber Masse N negatives Einschaltsignal am Eingang IN zugeführt werden. In diesem Fall wird der Kondensator C05 durch die positive Halbwelle der an der Versorgungsspannungsklemme L stehenden Wechselspannung über die Widerstände R01 und R05 aufgeladen, während die negative Halbwelle von Masse N über die Erregerwicklung PV des Zündbrennerventils, den Ruhekontakt PNC des Strömungsschalters PS und die Diode D04 sowie den Widerstand R01 zur Klemme L fließt. Das Zündbrennerventil PV wird durch diesen Strom nicht zum Ansprechen gebracht. Bei durchgeschaltetem Transistor Q03 könnte der Kondensator C05 nicht aufgeladen werden. Seine Aufladung erfolgt solange bis die Spannung am nicht invertierenden Eingang (+) des Vergleichers IC1 diejenige am invertierenden Eingang (-) überschreitet. In diesem Fall nimmt der Ausgang des Vergleichers IC01 eine hohe Impedanz an, so daß ein Strom von der Spannungsquelle (+Vc) über den Widerstand R10 in die Basis des Transistors QO2 fließt und diesen durchschaltet. Die Ladung auf dem Kondensator C05 reicht aus, um mit dem Durchschalten des Transistors Q02 das Relais RY02 zum Ansprechen zu bringen. Sein Umschaltkontakt ry02 schaltet vom Ruhekontakt NC2 auf den Arbeitskontakt NO2 um. Nunmehr liegt das Gebläse FA über den letztgenannten Kontakt an der Versorgungswechselspannung L und läuft an. Zugleich fließt ein positiver Strom i1 von der Leitung L über den Kontakt NO2, die Diode DO2, den Widerstand RO2 und von dort in den Kondensator CO1, und zwar solange wie die Spannung an diesem Kondensator kleiner ist als die Durchbruchsspannung der Zenerdiode Z01. Überschreitet die Spannung am Kondensator CO1 die Spannung an der Zenerdiode Z01, so fließt der Strom i1 über die Zenerdiode Z01 das Relais RY02 und den Transistor Q02 nach Masse. Dieser Strom i1 dient als Haltestrom für das Relais RY02.The circuit arrangement works as follows:
The circuit shows that switching on the contact ry02 of the relay RY02 is necessary to switch on the fan FA. This relay can only respond when transistor QO2 is on and transistor QO3 is off. For this purpose, the base of the transistor QO3 must be supplied with a switch-on signal which is negative with respect to ground N at the input IN. In this case, the capacitor C05 is charged by the positive half-wave of the AC voltage at the supply voltage terminal L via the resistors R01 and R05, while the negative half-wave by ground N via the field winding PV of the pilot burner valve, the normally closed contact PNC of the flow switch PS and the diode D04 and resistor R01 flows to terminal L. The pilot burner valve PV is not activated by this current. With transistor Q03 turned on, capacitor C05 could not be charged. It is charged until the voltage at the non-inverting input (+) of the comparator IC1 exceeds that at the inverting input (-). In this case, the output of the comparator IC01 assumes a high impedance, so that a current flows from the voltage source (+ Vc) via the resistor R10 into the base of the transistor QO2 and turns it on. The charge on capacitor C05 is sufficient to trigger relay RY02 when transistor Q02 is turned on. Its changeover contact ry02 switches from normally closed contact NC2 to normally open contact NO2. The fan FA is now connected to the AC supply voltage L via the latter contact and starts up. At the same time, a positive current i1 flows from line L via contact NO2, diode DO2, resistor RO2 and from there into capacitor CO1, as long as the voltage across this capacitor is less than the breakdown voltage of zener diode Z01. If the voltage across capacitor CO1 exceeds the voltage across Zener diode Z01, current i1 flows through Zener diode Z01, relay RY02 and transistor Q02 to ground. This current i1 serves as a holding current for the relay RY02.
Sobald das Gebläse FA angelaufen ist, schaltet der Strömungsschalter PS vom Ruhekontakt PNC auf den Arbeitskontakt PNO um, so daß nunmehr auch die Erregerwicklung PV des Zündbrennerventils mit Strom versorgt wird, das Ventil öffnet und Gas zum Zündbrenner fließt. Zugleich erhält über den Ruhekontakt NC1 des Relais RY01 der Zündstromkreis Z Spannung und erzeugt über den Zündtransformator T1 in Reihe mit einem spannungsabhängigen Widerstand RV01 an der Zündelektrode HT Hochspannungszündfunken gegenüber Erde GND.As soon as the fan FA has started, the flow switch PS switches from the normally closed contact PNC to the normally open contact PNO, so that the excitation winding PV of the pilot burner valve is now supplied with current, the valve opens and gas flows to the pilot burner. At the same time, the ignition circuit Z receives voltage via the normally closed contact NC1 of the relay RY01 and generates high-voltage ignition sparks to earth GND via the ignition transformer T1 in series with a voltage-dependent resistor RV01 at the ignition electrode HT.
Wenn sich eine Zündflamme gebildet und stabilisiert hat, fließt zum Eingang E des Flammenfühlerschaltkreises FS von der Flammenstabelektrode HT über die Sekundärwicklung des Transformators T1 ein Ionisationsstrom, so daß der Ausgang A des Flammerfühlerschaltkreises FS auf eine hohe Impedanz umschaltet. Der Strom über den Widerstand R06 fließt nunmehr nicht länger über den Ausgang A und den Flammenfühlerschaltkreis nach Masse N, sondern über die Diode D06 in die Basis des Transistors Q01, so daS dieser durchschaltet. Damit kann die auf dem Kondensator C01 gespeicherte Ladung das Relais RY01 zum Ansprechen bringen. Da der vom Strom i1 am Relais RY01 erzeugte Spannungsabfall geringer ist als die Spannung an der Zenerdiode Z01, fließt der Strom i1 voll durch das Relais RY01 und reicht aus, um das Relais angesprochen zu halten. Sollte infolge eines Fehlers der Transistor Q01 kurzgeschlossen sein, so kann das Relais RY01 nicht ansprechen.When a pilot flame has formed and stabilized, an ionization current flows to the input E of the flame sensor circuit FS from the flame rod electrode HT via the secondary winding of the transformer T1, so that the output A of the flame sensor circuit FS switches to a high impedance. The current through resistor R06 now flows no longer via the output A and the flame sensor circuit to ground N, but via the diode D06 into the base of the transistor Q01, so that it switches through. The charge stored on capacitor C01 can thus trigger relay RY01. Since the voltage drop generated by the current i1 at the relay RY01 is less than the voltage at the zener diode Z01, the current i1 flows fully through the relay RY01 and is sufficient to keep the relay activated. If transistor Q01 is short-circuited due to an error, relay RY01 cannot respond.
Mit dem Ansprechen des Relais RY01 schaltet sein Umschaltkontakt ry01 auf den Arbeitskontakt NO1 um, wodurch einerseits der Zündstromkreis Z abgeschaltet und andererseits das Hauptgasventil MV mit Strom versorgt wird und öffnet. Damit ist der Brenner in seinen normalen Betriebszustand überführt.When the relay RY01 responds, its changeover contact ry01 switches over to the normally open contact NO1, which on the one hand switches off the ignition circuit Z and on the other hand supplies and opens the main gas valve MV. The burner is now in its normal operating state.
Sollte während des Normalbetriebs der Übertemperaturbegrenzer HL ansprechen, so fällt das Relais RY01 ab, wodurch das Hauptgasventil MV stromlos wird und schließt. Der Zündbrenner hingegen wird weiterhin mit Gas versorgt. Da die Zündflamme somit weiterbrennt, bleibt der Transistor Q01 durchgeschaltet. Sobald der Übertemperaturbegrenzer HL infolge Abkühlung wieder schließt, kann das Relais RY01 nicht wieder ansprechen, weil der Kondensator C01 während der Abschaltdauer nicht auf eine hinreichend hohe Spannung aufgeladen werden konnte. Er war nämlich während der Abkühlzeit über die Relaiswicklung RY01 und den Transistor Q01 praktisch kurzgeschlossen und entladen worden. Zum Wiedereinschalten der Anlage muß deshalb entweder die Netzwechselspannung unterbrochen oder das Eingangssignal IN vorübergehend abgeschaltet werden, damit das Relais RY02 abfällt und die Zündflamme erlischt.If the overtemperature limiter HL responds during normal operation, the relay RY01 drops out, as a result of which the main gas valve MV is de-energized and closes. The pilot burner, however, continues to be supplied with gas. Since the pilot flame continues to burn, the transistor Q01 remains on. As soon as the overtemperature limiter HL closes again due to cooling, the relay RY01 cannot respond again because the capacitor C01 could not be charged to a sufficiently high voltage during the switch-off period. It was in fact short-circuited and discharged via the relay winding RY01 and the transistor Q01 during the cooling down period. To switch the system on again, the AC mains voltage must therefore either be interrupted or the input signal IN temporarily switched off. so that the relay RY02 drops out and the pilot light goes out.
Aus der geschilderten Betriebsweise ergibt sich, daß der Brenner nur in Gang gesetzt werden kann, wenn sich der Strömungsschalter PS anfänglich in der Ruhestellung befindet, in der sein Ruhekontakt PNC geschlossen ist. Ferner muß ein negatives Eingangssignal IN vorhanden sein und somit der Transistor Q03 gesperrt sein. Schließlich besteht eine dritte Bedingung darin, daß der Flammenfühlerschaltkreis FS keine Flamme feststellt. Wenn eine dieser Bedingungen nicht erfüllt ist, kann die Steuerschaltung nicht anlaufen. Liegt beispielsweise der Strömungsschalter mit seinem Umschaltkontakt am Arbeitskontakt PNO, so wird der Kondensator C05 nicht aufgeladen, weil die Diode D04 wirkungslos ist. Wäre der Transistor Q03 aufgrund eines positiven Eingangssignals durchgeschaltet, so würde er den Kondensator C05 kurzschließen, so daß dieser ebenfalls nicht aufgeladen werden könnte. Wird vor dem Einschalten der Anlage bereits eine Flamme festgestellt oder vom Flammenfühlerschaltkreis FS das Vorhandensein einer Flamme fälschlich simuliert, so nimmt sein Ausgang A eine hohe Impedanz an, verbindet also nicht mehr den Widerstand R15 niederohmig mit Masse N. Damit findet keine Teilung der Spannung des Kondensators C05 über den Spannungsteiler R13, R15 statt, so daß am nicht invertierenden Eingang (+) des Vergleichers IC1 die volle Spannung des Kondensators C05 liegt. Damit wird, wie oben erwähnt, der Transistor Q02 zu einer Zeit durchgeschaltet, wenn die Spannung am Kondensator C05 noch viel zu niedrig ist, um das Relais RY02 zum Ansprechen zu bringen.It follows from the described mode of operation that the burner can only be started when the flow switch PS is initially in the rest position in which its normally closed contact PNC is closed. Furthermore, a negative input signal IN must be present and the transistor Q03 must therefore be blocked. Finally, a third condition is that the flame sensor circuit FS does not detect a flame. If one of these conditions is not met, the control circuit cannot start. If, for example, the flow switch with its changeover contact is connected to the make contact PNO, the capacitor C05 is not charged because the diode D04 has no effect. If the transistor Q03 were turned on due to a positive input signal, it would short-circuit the capacitor C05, so that it could not be charged either. If a flame is already detected before the system is switched on or the presence of a flame is incorrectly simulated by the flame sensor circuit FS, its output A assumes a high impedance, i.e. it no longer connects the resistor R15 to ground N with a low impedance Capacitor C05 via the voltage divider R13, R15 instead, so that the full voltage of the capacitor C05 is at the non-inverting input (+) of the comparator IC1. Thus, as mentioned above, transistor Q02 is turned on at a time when the voltage on capacitor C05 is still too low to make relay RY02 respond.
Der Strömungsschalter PS bildet mit seinem Ruhekontakt PNC zusammen mit den Widerständen R01 und R04 sowie der Diode D04 und dem Zündbrennerventil PV einen Ladestromkreis für den Kondensator C05, der die zum Einschalten des Relais RY02 erforderliche Energie zur Verfügung stellt. Der Arbeitskontakt PNO des Strömungsschalters dient der Einschaltung des Zündbrennerventils PV, nachdem das Relais RY02 angesprochen hat. Die Schaltungsanordnung ist weitgehend eigensicher. Sie kann durch ein Niedervolt-Steuersignal am Eingang IN ohne zusätzliches Relais eingeschaltet werden und ist somit unmittelbar aus einem elektronischen Temperaturregler ansteuerbar.The flow switch PS forms with its normally closed contact PNC together with the resistors R01 and R04 as well as the diode D04 and the pilot burner valve PV a charging circuit for the capacitor C05, which provides the energy required to switch on the relay RY02. The make contact PNO of the flow switch serves to switch on the pilot burner valve PV after the relay RY02 has responded. The circuit arrangement is largely intrinsically safe. It can be switched on by a low-voltage control signal at the IN input without an additional relay and can therefore be controlled directly from an electronic temperature controller.
Claims (10)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP92107000A EP0566768B1 (en) | 1992-04-24 | 1992-04-24 | Control circuit for a gas burner with a flow switch for monitoring the air supply |
DE59203393T DE59203393D1 (en) | 1992-04-24 | 1992-04-24 | Control circuit for gas burners with a flow switch for monitoring the air supply. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP92107000A EP0566768B1 (en) | 1992-04-24 | 1992-04-24 | Control circuit for a gas burner with a flow switch for monitoring the air supply |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0566768A1 true EP0566768A1 (en) | 1993-10-27 |
EP0566768B1 EP0566768B1 (en) | 1995-08-23 |
Family
ID=8209571
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92107000A Expired - Lifetime EP0566768B1 (en) | 1992-04-24 | 1992-04-24 | Control circuit for a gas burner with a flow switch for monitoring the air supply |
Country Status (2)
Country | Link |
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EP (1) | EP0566768B1 (en) |
DE (1) | DE59203393D1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0698767A1 (en) * | 1994-08-24 | 1996-02-28 | Honeywell B.V. | Control circuit for a gas burner with monitoring of the combustion air supply |
CN101728232B (en) * | 2008-10-22 | 2012-07-04 | 北京中科信电子装备有限公司 | Control method for preventing process gas from mixing from hardware |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3710192A (en) * | 1971-06-18 | 1973-01-09 | Gen Electric | Burner ignition system |
CH648108A5 (en) * | 1984-02-15 | 1985-02-28 | Landis & Gyr Ag | SWITCHING FOR A BURNER. |
EP0440872A2 (en) * | 1990-02-06 | 1991-08-14 | Honeywell B.V. | Ignition and safety circuit for gas burners |
-
1992
- 1992-04-24 DE DE59203393T patent/DE59203393D1/en not_active Expired - Fee Related
- 1992-04-24 EP EP92107000A patent/EP0566768B1/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3710192A (en) * | 1971-06-18 | 1973-01-09 | Gen Electric | Burner ignition system |
CH648108A5 (en) * | 1984-02-15 | 1985-02-28 | Landis & Gyr Ag | SWITCHING FOR A BURNER. |
EP0440872A2 (en) * | 1990-02-06 | 1991-08-14 | Honeywell B.V. | Ignition and safety circuit for gas burners |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 6, no. 33 (M-114)27. Februar 1982 & JP-A-56 149 528 ( NISSAN MOTER ) * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0698767A1 (en) * | 1994-08-24 | 1996-02-28 | Honeywell B.V. | Control circuit for a gas burner with monitoring of the combustion air supply |
CN101728232B (en) * | 2008-10-22 | 2012-07-04 | 北京中科信电子装备有限公司 | Control method for preventing process gas from mixing from hardware |
Also Published As
Publication number | Publication date |
---|---|
EP0566768B1 (en) | 1995-08-23 |
DE59203393D1 (en) | 1995-09-28 |
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